Blocking oscillator for a reciprocating electromagnetic actuator

Abstract

A blocking oscillator for a reciprocating electromagnetic actuator having a solenoid coil, a detection coil for generating a control signal in response to a charge in the magnetic field generated by the solenoid coil, a silicon Darlington amplifier responsive to the control signal to control the current through said solenoid coil, and a diode connected in series with the collector of the Darlington amplifier rendering the Darlington amplifier immune to reverse voltage and transient signals.

What is claimed is: 
     
       1. A blocking oscillator for reciprocating a biased armature comprising: a solenoid coil for generating a magnetic field operative to move said biased armature in response to a current flow therethrough, said solenoid coil having an input end and an output end;   detection coil means magnetically coupled to said solenoid coil for producing a control signal in response to a change in said magnetic field generated by said solenoid coil, said detection coil means having one end connected to said output end of said solenoid coil and an opposite end;   transistor means having an emitter connected to said output end of said solenoid coil, a collector and a base;   doide means having an anode connected to said collector of said transistor means and a cathode;   a pair of resistances, forming a voltage divider, connected between said opposite end of said detection coil means and said cathode of said diode means; and   a resistance interconnecting said base of said transistor means with the junction between said pair of resistances.   
     
     
       2. The blocking oscillator of claim 1 wherein said transistor means is a high gain silicon Darlington amplifier. 
     
     
       3. The blocking oscillator of claim 1 wherein said transistor means is a high gain single silicon transistor. 
     
     
       4. The blocking oscillator of claim 1 wherein said detection coil means comprises: a spool having an inner diameter; and   a first predetermined number of turns of a first wire wound around said inner diameter.   
     
     
       5. The blocking oscillator of claim 4 wherein said solenoid coil comprises a second predetermined number of turns of a second wire wound over said first predetermined number of turns of said first wire. 
     
     
       6. The blocking oscillator of claim 5 wherein said first wire has a diameter significantly smaller than said second wire. 
     
     
       7. The blocking oscillator of claim 1 wherein said solenoid coil and said detection coil means comprises: a spool having an inner diameter;   a first predetermined number of turns of a fine wire wound about said inner diameter of said spool to form said detection coil means; and   a second predetermined number of turns of a coarse wire wound over said first predetermined number of turns of fine wire to form said solenoid coil.   
     
     
       8. The blocking oscillator of claims 1 or 2 further comprising current dissipator means for dissipating the current induced in said solenoid coil by the collapsing magnetic field when said transistor means is turned off, said current dissipator means connected in parallel with at least said solenoid coil. 
     
     
       9. The blocking oscillator of claim 8 wherein said current dissipator means comprises a first serially connected diode and resistance connected between said input and output ends of said solenoid coil. 
     
     
       10. The blocking oscillator of claim 8 wherein said current dissipator means comprises a first serially connected diode and resistance between the input end of said solenoid coil and said opposite end of said detection coil means. 
     
     
       11. The blocking oscillator of claim 10 wherein said current dissipator means further comprises a second serially connected diode and resistance connected between said input and output ends of said solenoid coil. 
     
     
       12. A blocking oscillator comprising: a spool having an inner diameter;   a first predetermined number of turns of a first wire wound around said inner diameter, said first wire having a first end and a second end;   a second predetermined number of turns of a second wire wound over said first predetermined number of turns, one end of said second wire adapted to receive a positive electrical potential from an external source and an opposite end connected to said first end of said first wire;   a high gain silicon Darlington amplifier having an emitter connected to the opposite end of said second wire, a collector, and a base;   a diode having an anode connected to the collector of said Darlington amplifier and a cathode adapted to receive a negative electrical potential from said source of electrical power; and   a pair of resistances serially connected between said second end of said first wire and said cathode of said diode, the junction between said pair of resistances connected to said base of said Darlington amplifier.   
     
     
       13. The blocking oscillator of claim 12 further comprising a second resistance connected between said junction of said pair of resistances and said base of said Darlington amplifier. 
     
     
       14. The blocking oscillator of claims 12 or 13 further comprising first current dissipator means connected in parallel with said second predetermined number of turns of said second wire. 
     
     
       15. The blocking oscillator of claim 14 wherein said first current dissipator means comprises a first serially connected diode and resistance connected between said one end and said opposite end of said second wire. 
     
     
       16. The blocking oscillator of claim 15 further including second current dissipator means comprising a second serially connected diode and resistance connected between said one end of said second wire and said second end of said first wire.